PROJECT SUMMARY/ABSTRACT Parkinson?s disease (PD) is a progressive, neurodegenerative disease that impacts multiple sensorimotor systems, including communication and swallowing. Disordered communication and swallowing in PD can result in severe negative health and psychosocial consequences. Early identification of communication and swallowing changes has the potential to improve outcomes in these patients. However, changes in communication and swallowing function in early PD are subtle, and therefore difficult to identify with current clinical methods. The proposed research aims to narrow this significant gap in clinical practice by identifying and developing tests that can detect subtle changes in cranial and limb movements in early PD. An ideal candidate variable for determining early sensorimotor deficits is within-individual motor variability. Variability in repeated limb movements has been established as a clinical sign in early PD. However, this has not fully been determined in communication, and only recently done so by our laboratory for swallowing behaviors. The proposed research will assemble a battery of tests to evaluate motor variability in the domains of voice, swallowing, gait, and finger-tapping. Because the onset and progression of PD is often monitored by deficits in limb function and because limb and cranial motor function dissociate in terms of treatment, it is important to determine how changes in voice and swallowing are related to limb deficits. Further, detecting subtle motor variability could aid in diagnosis of early/pre-clinical PD. As such, the proposed research has two specific aims: 1) To characterize relationships among and between cranial and limb motor variability in patients with PD and 2) To identify the cranial and/or limb assays reflecting motor variability that will accurately identify patients with early PD from age- and sex-matched healthy controls. To address these aims, we will evaluate motor variability in patients with early-stage PD in order to determine profiles of cranial and limb motor changes and then use these variables to classify patients with early PD vs. age and sex-matched controls. Our central hypotheses are that: a) patients with PD will exhibit within-individual motor variability in voice, swallowing, and limb motor tasks separately, but will show patterns of motor variability that manifest as more of a cranial or limb motor profile; and b) cranial and/or limb motor variability will sufficiently differentiate individuals with PD from healthy controls. Communication and swallowing deficits are under- diagnosed and under-treated in PD, representing a significant detriment to health and quality of life. Results from these studies can provide improved clinical methods to identify early and subtle communication and swallowing dysfunction in PD. Early diagnosis can then lead to optimized treatments, including neuroprotective strategies.